Gondwanan deglaciation and opening of Neotethys: the Al Khlata and Saiwan Formations of Interior Oman

Angiolini, Lucia; Balini, Marco; Garzanti, Eduardo; Nicora, Alda; Tintori, Andrea

doi:10.1016/s0031-0182(03)00315-8

Cited by 90 publications

(99 citation statements)

References 48 publications

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“…In the topmost 1 m of Section One at Ricklow Quarry, Shannon-Wiener diversity values of 0.45 -0.65 over four consecutive divisions may reflect an intermediate point in the ecological succession between the early and mature stages, as already observed in other Palaeozoic brachiopodbearing successions (e.g. Angiolini et al 2003;Angiolini 2007). Therefore, the palaeocommunity dominated by Gigantoproductus species was rapidly established, but did not evolve towards a climax.…”

Section: Palaeoecological Interpretation Of the Gigantoproductus Floamentioning

confidence: 75%

Sedimentary context and palaeoecology of Gigantoproductus shell beds in the Mississippian Eyam Limestone Formation, Derbyshire carbonate platform, central England

Nolan

Angiolini

Jadoul

et al. 2017

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A sedimentological study was conducted at two localities exposing the Mississippian Eyam Limestone Formation of the Derbyshire carbonate platform, UK. Ricklow Quarry comprises seven facies with diverse skeletal assemblages, representing deposition on the inner to middle ramp within open marine waters. Once-a-Week Quarry comprises four facies, dominated by crinoidal debris representing deposition on the inner ramp. Both localities expose Gigantoproductus shell beds. Palaeoecological analysis of a single shell bed from each locality enabled investigation of the rapid colonization and success of this taxon on the platform. At Ricklow Quarry, on the eastern side of a localized mud mound, both life (>72% of thin and thick-shelled brachiopods in life position) and neighbourhood assemblages are present. A low-moderate diversity community (<1.37 and <0.8 Shannon diversity index) rapidly established over relict Brigantian mud mounds. Shell beds are preluded by intervals of decreased energy that allowed larvae to settle. Once established, the dominance of thick-shelled individuals enabled baffling, potentially providing localized shelter for larvae and nearby individuals. At Once-a-Week Quarry, where no mud mound is present, only thick-shelled Gigantoproductus species and a low diversity community (<1.07 Shannon diversity index) exclusively comprising neighbourhood assemblages (37% in life position) is present. The presence of inactive mud mounds at Ricklow Quarry appears to have been the key to the success of Gigantoproductus species enabling the onset of stable communities in the shelter provided by the relict mound. Once the first palaeocommunities were established, larvae dispersed and colonized higher energy settings, such as at Once-a-Week Quarry.

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Section: Palaeoecological Interpretation Of the Gigantoproductus Floamentioning

confidence: 75%

Sedimentary context and palaeoecology of Gigantoproductus shell beds in the Mississippian Eyam Limestone Formation, Derbyshire carbonate platform, central England

Nolan

Angiolini

Jadoul

et al. 2017

PYGS

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“…In the northwestern Himalaya, Neotethyan rifting reached its climax with the onset of bimodal volcanism and intrusion of alkali granites, dated radiometrically at 284 þ 1 Ma (U^Pb on zircons [42]), and biostratigraphically constrained to the earliest Permian [43,44]. Break-up and formation of oceanic crust followed shortly afterwards from the Himalayas all the way to northern Oman at mid-Early Permian times (midSakmarian [45,46]). …”

Section: Early Permian Pangea 'B' To Late Permianmentioning

confidence: 99%

Early Permian Pangea ‘B’ to Late Permian Pangea ‘A’☆

Muttoni¹,

Kent²,

Garzanti³

et al. 2003

Earth and Planetary Science Letters

223

151

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The pre-drift Wegenerian model of Pangea is almost universally accepted, but debate exists on its pre-Jurassic configuration since Ted Irving introduced Pangea 'B' by placing Gondwana farther to the east by V3000 km with respect to Laurasia on the basis of paleomagnetic data. New paleomagnetic data from radiometrically dated Early Permian volcanic rocks from parts of Adria that are tectonically coherent with Africa (Gondwana), integrated with published coeval data from Gondwana and Laurasia, again only from igneous rocks, fully support a Pangea 'B' configuration in the Early Permian. The use of paleomagnetic data strictly from igneous rocks excludes artifacts from sedimentary inclination error as a contributing explanation for Pangea 'B'. The ultimate option to reject Pangea 'B' is to abandon the geocentric axial dipole hypothesis by introducing a significant non-dipole (zonal octupole) component in the Late Paleozoic time-averaged geomagnetic field. We demonstrate, however, by using a dataset consisting entirely of paleomagnetic directions with low inclinations from sampling sites confined to one hemisphere from Gondwana as well as Laurasia that the effects of a zonal octupole field contribution would not explain away the paleomagnetic evidence for Pangea 'B' in the Early Permian. We therefore regard the paleomagnetic evidence for an Early Permian Pangea 'B' as robust. The transformation from Pangea 'B' to Pangea 'A' took place during the Permian because Late Permian paleomagnetic data allow a Pangea 'A' configuration. We therefore review geological evidence from the literature in support of an intra-Pangea dextral megashear system. The transformation occurred after the cooling of the Variscan mega-suture and lasted V20 Myr. In this interval, the Neotethys Ocean opened between India/Arabia and the Cimmerian microcontinents in the east, while widespread lithospheric wrenching and magmatism took place in the west around the Adriatic promontory. The general distribution of plate boundaries and resulting driving forces are qualitatively consistent with a right-lateral shear couple between Gondwana and Laurasia during the Permian. Transcurrent plate boundaries associated with the Pangea transformation reactivated Variscan shear zones and were subsequently exploited by the opening of western Neotethyan seaways in the Jurassic.0012-821X / 03 / $^see front matter ß

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“…The Al Khlata Formation consists of a complex package of clastic lithologies that range from conglomerates through diamictites, gravels, pebbly sandstones, siltstones to silty shales (Braakman et al, 1982;Hughes Clarke, 1988;Levell et al, 1988;Dubreuilh et al, 1992;Roger et al, 1992;Al-Belushi et al, 1996;Angiolini et al, 2003). The glaciogenic nature of the Al Khlata Formation was established from studies of the outcrop area on the western flank of the Haushi-Huqf Uplift where striated pavements of the Precambrian Khufai Formation have been found (Braakman et al, 1982;Al-Belushi et al, 1996).…”

Section: Introductionmentioning

confidence: 99%

A High Resolution Palynozonation for the Al Khlata Formation (Pennsylvanian to Lower Permian), South Oman

Penney¹,

Barram²,

Stephenson³

2008

Palynology

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Palynology is the main method of correlating the subsurface glaciogenic Al Khlata Formation of Oman, due to extreme lateral variability of facies, and poor seismic resolution. The chief 2 operating company in Oman, Petroleum Development Oman, has developed a robust in-house palynozonation through almost 40 years of exploration and production based on thousands of samples and hundreds of well sections. In this paper the formal definitions of the biozones are published, and the biozones are correlated in detail with faunally-calibrated palynological biozones in Western Australia, thereby allowing correlation with the standard Russian stages.Seven biozones are distinguished. The oldest, biozones 2159A and B, of probable late Pennsylvanian age, are characterised by low diversity assemblages of Punctatisporites and monosaccate pollen, with Biozone 2159A having a lower proportion of monosaccate pollen than Biozone 2159B. Biozone 2165A, of probable Asselian age, is characterised by common cingulicamerate spores and Microbaculispora Group; while Biozone 2165B contains in addition to the above, common Horriditriletes Group, and is likely to be Asselian-Sakmarian in age. Biozone 2141A is characterised by common taeniate and non-taeniate bisaccate pollen and Cycadopites cymbatus, particularly toward the top; and the succeeding 2141B by

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Gondwanan deglaciation and opening of Neotethys: the Al Khlata and Saiwan Formations of Interior Oman

Cited by 90 publications

References 48 publications

Sedimentary context and palaeoecology of Gigantoproductus shell beds in the Mississippian Eyam Limestone Formation, Derbyshire carbonate platform, central England

Sedimentary context and palaeoecology of Gigantoproductus shell beds in the Mississippian Eyam Limestone Formation, Derbyshire carbonate platform, central England

Early Permian Pangea ‘B’ to Late Permian Pangea ‘A’☆

A High Resolution Palynozonation for the Al Khlata Formation (Pennsylvanian to Lower Permian), South Oman

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